KR100677011B1 - Tunable optical add/drop multiplexer - Google Patents

Abstract

The present invention relates to an optical signal device, a wavelength division multiplexer / demultiplexer optical device and a method of implementing the same, wherein the coating layer 4 comprises a grating and is made of a material whose refractive index is modulated (eg, by a heater). It can reflect a predetermined wavelength of light. Thus, a single optical signal device can be used to select various separation wavelengths.

Optical signal device, multiplexer, heater, refractive index, grating.

Description

Variable Optical Add / Drop Multiplexers {TUNABLE OPTICAL ADD / DROP MULTIPLEXER}

The present invention relates to an improved integrated wavelength division multiplexer / demultiplexer optics in which light of a particular wavelength (or specific wavelength) can be added or reduced effectively. The device can be made of an optical polymer whose refractive index varies greatly with temperature. For dynamic wavelength selection, a single filter element can be used over a wide wavelength range.

D.C. in 1987 Electronics , Vol. 23, pp. 668-669. Johnson, K. Oh. Hill, f. Virodu, and S. Poucher's "New Design Concepts for Narrow-band Wavelength Selective Optical Taps and Couplers " and the 1995 IOOC Method , pp. 66-67. As disclosed in Gils and V. Mizrahi, "Low Loss Add / Drop Multiplexers for WDM Optical Wave Networks," devices are known in the art for adding / dropping wavelength coded signals (light of a particular wavelength or wavelengths). Such devices use optical fibers that are widely used in telecommunication systems, as well as local area networks, computer networks and their equivalents. An optical fiber can transmit a large amount of information, and the device of the present invention is intended to extract / inject a selected amount of information from or to the fiber by separating information transmitted on different wavelength channels.

This type of device includes various elements that separate the wavelength coded signals together. E. J., 1969, page 2071, Bell Systems Technology Journal . As disclosed in Markatili's "Insulated Couplers and Integral Rectangular Waveguides for Integrated Optics," integrated optical couplers, in particular directional couplers, have been developed to implement instant directional coupling. The optical signal is coupled from one planar waveguide to another planar waveguide. The signal of the second planar waveguide propagates in the same direction as the signal moves in the first planar waveguide.

L. B., 1995, J. Lightwave Technology, Vol. 13, pp. 615-627. Soldano and E.C.M. As disclosed in Pennings'"self-imaging based optical multimode interference device; its principles and applications", MMI (multimode interference) couplers have been developed to implement coupling. The MMI coupler implements self-imaging, but the field profile input to the multimode waveguide is reproduced as single or multiple images at periodic intervals along the waveguide propagation direction.

Optical circulators are optical coupling devices having at least three ports. The three-port circulator couples the light input to port 1 to port 2, the light input to port 2 to port 3, and the light input to port 3 to port 1.

K. Oh, 1997, J. Lightwave Technology, Vol. 15, pages 1263-1276. Hill and edge. "The principles and outline of the grid fabric breather Technology" melcheu and 1997, as disclosed in "Fiber grating spectra," between, "J. Lightwave Technology" claim 15 in tea. 1277-1294 of the page, isolating a narrow band of wavelengths Diffraction gratings (e.g., Bragg gratings) are used for this purpose. L. Eldada, S., " Optical Technology, " Volume 10, pages 1416-1418, 1998. Yin. Cargar, Mr. Glass, R. As disclosed in Bromquist and R. Norwood's "Integrated Multichannel OADM Using Polymer Bragg Lattice MZI," such a grating reflector disturbs other signals of different wavelengths in or from the fiber optical transmission system. It is possible to construct a device used for adding or dropping a predetermined centered wavelength optical signal without making a change.

Rather than using multiple optical signal devices for the same purpose, it is desirable to be able to drop the wavelengths within the dynamic wavelength range of a single optical signal device more precisely than current devices.

The present invention relates to an optical signal device having fine modulation means for more effectively controlling the wavelength of light separated from a multi-wavelength optical signal.

The optical signal device of the present invention has a unique array of materials and includes varying the temperature of the optical signal device, thereby accurately selecting a target wavelength to add or drop the optical signal, and from one target wavelength to another. The wavelength changes quickly.

In particular, the optical signal device of the present invention

a) a substrate;

b) a pair of spaced coating layers of material having at least a similar refractive index;

c) a pair of opposing pairs disposed between the coating layer pairs having a refractive index greater than the refractive index of the coating layer so that a multi-wavelength optical signal can pass through the device in a single mode due to the difference in refractive index between the coating layer and the core layer. A core layer comprising a single waveguide or single waveguide;

d) a grating forming filter means for separating a single wavelength of light of said multi-wavelength optical signal; And

e) means for changing the refractive index of at least the core layer to control the wavelength of light separated from the multi-wavelength optical signal.

In a preferred configuration of the optical signal device, at least the core layer is made of a thermosensitive material, and the refractive index changing means heats the thermosensitive material. Throughout this specification, thermooptic effects, which are desirable refractive index altering effects, are used as exemplary effects. However, any refractive index changing effect (eg, electro-optic effect, stress optical effect) and any combination can be used in the present invention to change the refractive index.

 In a preferred configuration of the optical signal device, two coating layers are present between the refractive index changing means and the core, and the two coating layers each have a different refractive index. Also disclosed is a method of manufacturing the optical signal device of the present invention.

The accompanying drawings, in which like components are denoted by like reference numerals, illustrate embodiments of the present invention, and do not limit the present invention.

1 is a side view schematically showing an embodiment of a filter element of the optical signal device of the present invention,

FIG. 2 is a side view schematically showing another embodiment of a filter element of the optical signal device of the present invention using two coating layers having different refractive indices between the heater and the core layer, FIG.

3 is a graph showing the change in wavelength of light reflected by the filter element used in the present invention as a function of temperature,

4A-4C are schematic diagrams showing three embodiments of a single filter element according to the invention,

5A and 5B are schematic diagrams showing two embodiments of a two stage add / drop filter using two heaters with or without a switch according to the invention,

6A-6D are schematic diagrams of a four stage add / drop filter of the present invention with one or more heaters and various switch configurations,

7 is a schematic diagram of a four stage add / drop filter in accordance with the present invention in which unused channels are returned to the bus,

8 is a schematic diagram of a four stage add / drop filter of the present invention in which an unused channel is directly coupled with a pass line using a 1 × 5 combiner,

9 is a schematic diagram of a four stage add / drop filter according to the present invention which out-turns one edge of the filter to reduce the number of switches and the complexity of the coupler;

10 is a schematic diagram of a four stage add / drop filter according to the present invention which out-turns both edges of the filter to reduce the number of switches and the complexity of the coupler,

11 is a schematic diagram illustrating another embodiment of the four stage add / drop filter of the present invention with minimal switching of the switches and edges;

12 is a schematic diagram of a four stage add / drop filter of the present invention in which an unused channel is coupled with a pass line using an add filter.

FIELD OF THE INVENTION The present invention relates to an optical signal device, wherein means for modifying the refractive index, preferably using a heater and a thermosensitive polymer, are employed in the filter element (e.g., a Bregg grating) to select light in a wide range of wavelengths. To form a drop or add signal filter that can be finely modulated to drop or add a wavelength.

In a preferred form of the invention, a device in the form of a Mach Gender Interferometer, a 100% directional coupler, or a multimode interference (MMI) coupler with two coupling regions is employed. There is a lattice region consisting of a grating system (eg, a Bragg grating) between coupling regions comprising a 3 ms directional coupler or a 3 ms multimode interference coupler. The waveguides in the grating region of the Mach gendered device are spaced apart from one another so that no instantaneous coupling occurs in that region.

In another preferred form of the invention, a single waveguide is employed between the optical circulators. The waveguide has a grating region constituting a grating system.

According to a preferred form of the invention, the optical signal device is a thermosensitive material, i.e., a material having a thermo-optic coefficient (limited by a change in refractive index with temperature), for example, of which the absolute value is at least 10 ⁻⁴ / ° C. It has a lattice area with a unique configuration made of. Examples of thermosensitive polymers include crosslinked acrylates, polyamides and polymethylmethacrylates such as ethoxylated bisphenol diacrylate, tripropylene glycol diacrylate and 1,6-hexanediol diacrylate do.

If heating is at least a means of changing the refractive index of the core layer, the grating region is provided with other means capable of changing the temperature of the heater or polymer (such as an electrode of a specific resistance). Referring to Fig. 1, a first structure for the grating region of the optical device of the present invention is shown. The filter element 2 comprises a core region 4 with coating layers 6A and 6B on each side. A lattice is present in the core region 4, preferably additionally in the coating layers 6A and 6B. The heater 8 is present on the coating layer 6A, but may be an electrode having a specific resistance as described above. Below the lower coating layer 6B is a substrate 10. The core layer is made of a thermosensitive polymer as described above. The upper coating layer 6A and the lower coating layer 6B are also preferably made of a similar material, although the refractive index of each layer is different, as described below.

According to the invention, a heater for heating the thermosensitive polymer is provided near the filter element. As shown in FIG. 3, as the temperature of the filter element increases, the wavelength of the reflected light typically changes to a linear slope. As shown in the embodiment of FIG. 3, the wavelength of the reflected light is reduced to 0.256 nm / ° C. in the range of 2 to 100 ° C. FIG. The wavelength of the reflected light will vary linearly by about 20 nm within this temperature range. Thus, the present invention changes the wavelength of reflected light of the filter element of the optical signal device by raising or lowering the temperature of the material used to manufacture the filter element.

In the embodiment shown in FIG. 1, the refractive index n of the core 4 exceeds the refractive indices of both the upper coating layer 6A and the lower coating layer 6B. The refractive indices of the upper coating layer 6A and the lower coating layer 6B may be different as long as they are all smaller than the refractive index of the core layer, but the same is preferable.

In a preferred form of the present invention, the lower coating layer 6B has a thickness of about 10 to 20 mu m, while the upper coating layer 6A has a thickness of about 5 to 10 mu m. Preferably, the core layer has a thickness of about 3-9 μm.

A filter element suitable for use in the present invention is shown in FIG. 2. The filter element has an additional top coat layer 6C between the heater 8 and the top coat layer 6A. The additional top cladding layer 6C has a lower refractive index than the top cladding layer 6A, and is added because the metal element including the heater 8 tends to absorb light. The additional coating layer 6C serves to emit light from the heater to reduce the loss of the optical signal, while reducing the thicknesses 6A and 6C of the entire coating layer so that the core 4 can be efficiently driven by the heater 8. Allow to be heated.

In the embodiment shown in FIG. 2, the thickness of each layer is the same as described above in connection with the embodiment of FIG. 1. Preferably, the sum of the thicknesses of the top coating layers 6A and 6C is within about 5-10 m.

The present invention is directed to an N-stage based waveguide with a multi-stage optical signal device (e.g. a Mach gender or bidirectional coupler or insulator) for producing a drop filter that varies over a wide range (e.g., 24 to 100 nm). Single channel element). Heating means are provided in the filter element, and when the heating means are actuated, the action of heat on the polymeric material changes the reflected wavelength of the filter element.

Table 1 below shows the number N of steps required for a given fixed temperature range and wavelength modulation range. The value used for variability is 0.25 nm / ° C., which represents the linear relationship between the reflected wavelength and temperature described and shown in connection with the embodiment of FIG. 3.

Specific bandwidth  Temperature range  Modulation Range / Step 24 nm 32 nm 40 nm 80 nm 100 nm Number of 100 ㎓ (0.8 nm) channels 30 channels 40 channels 50 channels 100 channels 125 channels 10 ℃ 2.5 nm 10 steps Step 13 16 steps 32 steps 40 steps 20 ℃ 5.0 nm 5 steps 7 steps 8 levels 16 steps 20 steps 30 ℃ 7.5 nm 4 steps 5 steps 6 steps 11 steps Step 14 40 ℃ 10.0 nm Tier 3 4 steps 4 steps 8 levels 10 steps 50 ℃ 12.5 nm Tier 2 Tier 3 4 steps 7 steps 8 levels 100 ℃ 25.0 nm Stage 1 Tier 2 Tier 2 4 steps 4 steps

As shown in Table 1, for a given temperature range, there is a limit on how much modulation can occur per step. For example, in the 10 ° C. temperature range of the filter element, the modulation range for each step is 2.5 nm.

Depending on the bandwidth and channel span of the telecommunication system, the filter element will contain a certain number of channels. For example, if a telecommunications system has a bandwidth of 24 nm, there will be 30 channels at 0.8 nm per channel.

As shown in Table 1, it is easy to see the number of steps required for modulation in a given temperature range for a given bandwidth. For example, if the polymer material and the desired modulation rate allow a temperature range of 30 ° C., six steps are required with a channel span of 0.8 nm, a bandwidth of 40 nm, and a modulation range of 7.5 nm per step. If a smaller step is desired, a higher temperature range is required. Smaller steps make less insertion loss (the amount of light lost in ㏈ when passing through the device), but the speed at which the device is modulated to achieve a given wavelength is reduced.

If a large number of steps are used (ie low temperature range) for a given bandwidth, heat transfer is faster. However, more steps increase the length of the optical signal device, resulting in greater insertion loss. Therefore, it is preferred to operate in the appropriate number of steps in the intermediate temperature range of 10 to 100 ° C.

In addition, the number N of steps in Table 1 represents the M of the 1xM switch required to select a single stage output. The 1 × M switch may consist of a series of 1 × 2 switches (generally 1 × P switches, where P is less than M). When two outer stages are terminated by a slight temperature change outside of the modulation range, N becomes N-1. Since it is desirable to use large modulation capabilities to reduce the number of steps, it is not desirable to modulate the non-edge steps. However, while selective modulation means auxiliary spans and auxiliary heaters between segments with different heaters, the entire sample can be heated evenly if no external modulation is used. If outer modulation is used when the number of steps N is 2, no switching is necessary.

According to the present invention, by changing the temperature of the polymer material of the filter element, it is possible to control the wavelength falling in each step of the optical signal device. Changing the temperature causes the refractive index to change, which causes a change in wavelength of light that is added to or dropped from the multi-wavelength optical signal according to the equation below.

Where λ is the dropped or added wavelength, N is the effective refractive index of the material being heated, and Λ is the period of the grating.

Thus, the heating that changes N to a lower value Λ allows the added or dropped wavelength [lambda] to be changed.

The filter element employed in the present invention can be applied to various optical signal devices. 4A to 4C, three optical signal devices using the filter element 2 of the present invention shown in FIG. 1 or 2 are shown. 4A shows a Mach gender embodiment, FIG. 4B shows a 100% directional coupler embodiment, and FIG. 4C shows an embodiment in which a single waveguide is used between two three-port optical circulators 18. In three embodiments, the filter element comprises a heater 8 that intersects the grating region 20, as described above in connection with FIGS. 1 and 2. In operation, a multi-wavelength light source enters the grating region 20 through the input port 22. A single wavelength of light determined by the heater 8 is reflected according to the temperature of the grating region. While a single wavelength signal drops from the grating region through drop port 24, the remaining wavelengths of light pass through the grating region and exit "pass" port 26. The wavelength determined by the heater may be added to the wavelength exiting the pass port by being injected through the "additional" port 28. In the embodiment of FIG. 4A, the two 3-kHz couplers 12 may be 3-kHz MMI (multi-mode interference) couplers. In the embodiment of FIG. 4B, the 100% directional coupler 14 may be replaced with a 100% MMI coupler. In the embodiment of FIG. 4C, the three port optical circulator 18 may be replaced with 1 × 2 power splitters if it can withstand high insertion loss and high return reflectance.

By adjusting the heater according to the dependence of the reflected wavelength on the temperature shown in FIG. 3, the specific wavelength of light falling from or added to the light source can be accurately selected according to the invention. In the example shown in FIG. 3, for each ° C at which the temperature of the grating region rises, the reflected wavelength is reduced by 0.256 nm.

The remaining wavelengths of light passing through the filter elements shown in FIGS. 4A-4C can be further processed at other filter elements such that the two dropped wavelengths can be introduced into a single switch. In this way, one of the wavelengths can be lowered according to the needs of the user. This configuration is shown in Figures 5a and 5b.

Referring to FIG. 5A, two filter elements 2A and 2B with respective heaters 8A and 8B are used. The first selective wavelength λ ₁ is dropped from the filter element 2A and introduced into the 1 × 2 switch (denoted by reference numeral 30). The remaining light signal except λ ₁ passes through the second filter element 2B. The temperature of the heater is adjusted similarly to that shown in the example of FIG. 3 to drop another wavelength λ ₂ of light, which is introduced into the switch 30. In the embodiment shown in FIG. 5A, all wavelengths λ ₁ and λ ₂ are used as desired by the user, and the switch 30 is connected to any wavelength λ through the drop port 32 as required by the user. ₁ or λ ₂ ) can also be reduced. Preferably, the outer modulation is used in the unused stage so that no information in the unused range is lost.

The embodiment shown in FIG. 5B is similar to the embodiment of FIG. 5A, with the switch replaced by a circulator. In this embodiment, in order for only the desired wavelength to exit the drop port 32, outer modulation must be used.

The configuration shown in FIG. 5A exhibits some light intensity loss in the switch, while the configuration shown in FIG. 5B typically exhibits a large loss (about 3 dB), but this loss increases the modulation rate and / or further. It is acceptable when it is necessary to have more than one step to access a wide wavelength range.

The outer modulated wavelength is a wavelength outside the range of available wavelengths within the temperature range of the heater as shown in the example of FIG. For example, if the grating is in the form measured in FIG. 3 and the heater has a temperature range selected from 40 ° C. to 80 ° C., a variable wavelength is available in the range of about 1563 nm to 1553 nm. If the second grating is such, in the same temperature range it will filter out wavelengths in the range of 1553 nm to 1543 nm. Thus, the outside modulated wavelength corresponds to the outside of the full range (eg, 1564 nm or 1542 nm). Thus, referring to FIG. 5B, when λ ₁ is within the variable range and λ ₂ is the outer modulation wavelength, the only wavelength to be dropped by the combiner is λ ₁ .

A four-step configuration for reducing the selection wavelength by employing a heater according to the present invention is shown in FIGS. 6A-6D.

Referring to Figure 6A, an embodiment of the present invention employing a single heater and four stages using a 1x4 switch to reduce the desired wavelength signal is shown. In the embodiment shown in FIG. 6B, instead of the 1 × 4 switch shown in FIG. 6A, the same result was obtained using a series of 1 × 2 switches.

In the embodiment shown in FIG. 6C, two heaters were used to allow the edge step to be externally modulated. Three ports dropped the single wavelength optical signal through the 1 × 3 switch, and the fourth port dropped the fourth channel coupled with the output of the 1 × 3 switch to form the final drop port.

The embodiment shown in FIG. 6D uses two heaters and a 1 × 2 switch that allows the edge step to be modulated outside. The output of the 1 × 2 switch is combined to form the final drop port.

The output of the unused non-outer modulation phase includes information from the usable wavelength range, which information is preferably returned to the bus. This embodiment is shown in FIG. 7, where unused channels are collected and returned. In this embodiment, a 1 × 2 switch is provided at the output of each stage signaling to the drop or pass port. For example, a 6 kHz combiner may be used for the collection of unused channels in FIG. 7. For example, a 3 kHz coupler may be used to reinsert an unused channel into the bus.

As shown in the embodiment of FIG. 8, one way to reduce the loss of the collected channels to 7 dB is to route all four channels and combine them with pass lines using a 1 × 5 combiner. This increases the loss of the pass channel from 3 to 7 dB. This is acceptable because it equalizes all channels that pass through.

It is possible to modulate the edge stages in an environment that simplifies the optical circuit. As shown in FIG. 9, additional heaters are required, but no more than one 1 × 2 switch is required, and the 1 × 5 coupler of the pass ports is a 1 × 3 coupler that reduces the loss from 7 to 4.7 kW. As shown in FIG. 10, when one or more heaters are added, another 1 × 2 switch may be removed.

As another embodiment of the present invention, a variation of the embodiment shown in FIG. 10, a 1 × 4 coupler is provided in place of the 1 × 4 switch in the drop port as shown in FIG.

In another embodiment of the invention, which is a variation of the embodiment shown in FIG. 10, an additional filter is provided instead of a 1x3 switch in the pass port as shown in FIG. The addition filter has a lattice with the same period as the lattice of the corresponding add / drop filter and shares the same heater (or is generally heated to the same temperature) as the add / drop filter. The additive filter may have a very low light loss exceeding the N loss factor of the 1 × N coupler.

It can be seen that all configurations shown in the drop port of FIGS. 5-11 can be made in the additional port. In addition, all the multi-step configurations shown in FIGS. 5-11 using Mach gendered devices of the type shown in FIG. 4A are of a single waveguide between the three-port optical circulator of the type shown in FIG. 4C or of the type shown in FIG. 4B. It can be seen that 100% directional couplers can be used.

Claims (27)

a) a substrate; b) a pair of spaced apart first and second coating layers of at least a similar refractive index material; c) a refractive index greater than that of the first and second coating layers, disposed between the coating layer pairs, so that a multi-wavelength optical signal can pass through the device in a single mode due to the difference in refractive index between the coating layer and the core layer. A core layer comprising a pair of opposed waveguides or a single waveguide; d) a grating forms filter means for separating a single wavelength from light of said multi-wavelength optical signal, said grating being provided on each of said coating layer and said core layer to form a grating region; e) means for changing at least the refractive index of said core layer to control the wavelength of light separated from said multi-wavelength optical signal. 2. An optical signal device according to claim 1, wherein said at least core layer is made of a thermosensitive material and said means for changing at least the refractive index of the core layer comprises a heater. The optical signal device according to claim 1, wherein the device is in the form of a Mach gender interferometer with an integrated grating. 2. The optical signal device according to claim 1, wherein the device is in the form of a 100% MMI (multimode interference) coupler or a 100% directional coupler with an integrated variable grating. 2. The optical signal device according to claim 1, wherein the device is in the form of a single waveguide in which a variable grating is integrated between two 1x2 power splitters or two three-port optical circulators. 3. The optical signal device of claim 2, wherein the thermosensitive material has a relatively large thermo-optic coefficient with an absolute value of at least about 10 < ^-4 > 7. The optical signal device according to claim 6, wherein the thermosensitive material is at least one thermosensitive polymer. 8. The optical signal device according to claim 7, wherein the thermosensitive polymer is selected from the group consisting of crosslinked acrylates, polyamides and polymethylmethacrylates. The optical signal device according to claim 1, wherein the refractive indices of the first and second coating layers are the same. The optical signal device according to claim 1, further comprising a third coating layer disposed on the core layer. 11. The optical signal device according to claim 10, wherein the third coating layer has a smaller refractive index than the first and second coating layers. The optical signal device according to claim 1, wherein the core layer has a thickness of about 3 to 9 mu m. The optical signal device according to claim 1, wherein the second coating layer is located between the core layer and the substrate, and the thickness of the second coating layer is about 10 to 20 mu m. 2. The optical signal device as claimed in claim 1, wherein the first coating layer has a thickness of about 5 to 10 mu m. a) a substrate; b) a pair of spaced coating layers of material having at least a similar refractive index; c) a pair of opposing pairs disposed between the coating layer pairs having a refractive index greater than that of the coating layer, such that a multi-wavelength optical signal can pass through the device in a single mode due to the difference in refractive index between the coating layer and the core layer. A core layer comprising a waveguide or a single waveguide; d) a grating forms filter means for separating a single wavelength from light of said multi-wavelength optical signal, said grating being provided on each of said coating layer and said core layer to form a grating region; e) a wavelength division multiplexer / demultiplexer comprising a plurality of integrated optical signal devices each comprising means for changing the refractive index of at least the core layer to control the wavelength of light separated from the multi-wavelength optical signal Optical devices. 16. The optical device of claim 15, wherein the at least core layer is made of a thermosensitive material, and wherein the means for changing at least the refractive index of the core layer comprises a heater. 16. The optical device according to claim 15, wherein each of the plurality of integrated optical signal devices is in the form of a Mach gender interferometer with integrated variable gratings. 16. The optical device of claim 15, wherein each of the plurality of integrated optical signal devices is in the form of a 100% MMI (multi-mode interference) coupler or a 100% directional coupler in which a variable grating is integrated. 16. The optical device according to claim 15, wherein the plurality of integrated optical signal devices are each in the form of a single waveguide in which a variable grating is integrated between two 1x2 power splitters or two three-port optical circulators. 16. The optical device of claim 15, further comprising at least one switch receiving at least one selected wavelength from the optical signal device and selectively employing one of the received wavelengths. 16. The optical device of claim 15, further comprising at least one coupler for receiving at least one selected wavelength from the optical signal device. 16. The optical device according to claim 15, further comprising outer modulating means for outer modulating the wavelength of light from at least one of the optical signal devices. 23. The apparatus of claim 22, wherein the outer modulating means comprises gratings for different optical signal devices that filter different wavelength ranges, wherein at least one of the gratings reflects an outer modulating wavelength outside the range of unused wavelengths. Optical device. 16. The optical device of claim 15, further comprising means for returning at least one unused wavelength generated within the usable wavelength range to a non-isolated wavelength signal passing through the optical device. 25. The optical device of claim 24, further comprising an additional filter for returning unused wavelengths generated within the usable wavelength range to a non-isolated wavelength signal passing through the optical device. a) a substrate; b) a pair of spaced apart first and second coating layers of at least a similar refractive index material; c) a core layer having a refractive index greater than the refractive index of said first and second coating layers, said core layer comprising a pair of opposed waveguides or a single waveguide disposed between said pair of coating layers; d) a grating forms filter means for separating a single wavelength from light of said multi-wavelength optical signal, said grating being provided on each of said coating layer and said core layer to form a grating region; e) transmitting the optical signal through an optical signal device comprising means for changing at least the refractive index of the core layer; And And reflecting a predetermined wavelength of light by changing the refractive index. 27. The method of claim 26, wherein at least the core layer is made of a thermosensitive material, the optical signal device comprises a heater, and the method includes varying the temperature of the heater such that the thermosensitive material reflects a predetermined wavelength of light. And adding / dropping a predetermined wavelength of light with respect to an optical signal.

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